The present invention relates to a new and distinct variety of nectarine tree named ‘NJN100’. Our new tree resulted from crossing ‘B8-9-46-712034’ as the seed parent with ‘Eastern Glo’ nectarine tree, as the pollen parent. The new variety differs from seed parent ‘B8-9-46-712034’ (unpatented) in that the new variety has large, showy flowers and firm fruit with an attractive, glossy finish, while the seed parent has small, nonshowy flowers and comparatively soft fruit that usually have a poor finish. The new variety differs from pollen parent ‘Eastern Glo’ (U.S. Plant Pat. No. 7,890) in that the new variety has greyed-white flesh flecked with red, especially towards the skin, while the pollen parent has yellow to golden yellow flesh. The resulting tree was selected when growing in a cultivated area as the 4th tree in the 56th row of Block K at the Rutgers Fruit Research and Extension Center in Cream Ridge, N.J.